1. Field of the Invention
The present invention concerns a power chain consisting of at least a series of overlapping links held together by joints in front and back connections as seen in the direction of motion in the form of thrust shafts, between which are placed cooperating transmission pieces which upon rotation transmit a corresponding rotation to the next thrust shaft as seen in the direction of the chain motion.
2. Description of the Prior Art
Power transmission chains of the above type are used in stepless gears with smooth conical plate pairs. The chain is used with power dependent torque transmission, where the transmitted torque is completely dependent on the friction force in the contact points between the thrust shafts of the chain and the respective conical plate.
It is previously known to fix the rear thrust shaft within each link against rotation, as seen in the direction of motion of the chain, the primary object of the fixation being to guarantee that the oblique end surface to the utmost possible extent has the correct direction at its entrance and exit on the respective conical pair of plates. This has however hithereto not been solved. A further drawback of thrust shafts fixed against rotation and with oblique end surfaces is that their inclination does not correspond to the cone angle of the conical plate pairs, which means that actual contact force for the transmission of torque is concentrated at one point with very large contact pressures as a result.
In a known chain (U.S. Pat. No. 2,690,678) actuation of the following thrust shaft has been attempted through spring pieces between the thrust shaft of the chain but the springs are exposed to very large stresses and are therefore not appropriate, and they allow a proper adjustment of the thrust shaft only in the special case where the spring forces on both sides of the thrust shaft are equal. If not, a rotation torque occurs on the thrust shaft, with inequalities in chain speed during the entrance and exit of the chain as a result, which on one hand results in vibration disturbances and on the other hand in a detoriated efficiency. The reduction of efficiency is especially obvious at high chain speeds and low power outputs, or generally 5-10%. The periodically recurrent change of momentum along the free parts of the chain is especially inconvenient at the slack chain part, since variations in momentum cause large vibratory movements.